Steering mechanism



July 6,1954 KUTZLER 2,683,003

STEERING MECHANISM Filed Aug. 8, 1951 3 Sheets-Sheet l LEFT RIGHT AMP ELEVON EU; VON AMI? SERVO I SERVO 5 I 4 as I E gvA gR am. 00 P POSITION OT NETWORK 44 I I I01 I I I ELEVATOR I 85 I CONTROL I r ,42

' NETWORK 20 I I L 82 L 258 I I24 1 5 5 I l RUDDER r A qq CONTROL CONTROL NETWORK I I NETWORK I 266 25s I I RUDDER I i SERVO T AMPLIFIER I I I 226 r I I 251 I I I 3u-- I I l INVENTOR. LEFT RIGHT ROBERT J. KUTZLER RUDDER 204 RUDDER I 203 I I SERVO SERVO l BY I 4 I ATTORNEY Filed Aug. 8, 1951 3 Sheets-Sheet 2 VERTICAL y I GYROSGOPE I 2 4|I 42 IOI Ii 3 23 i 3 2 37' I as 26%;? I I I I I I IIS :66 I l l I I I l H. INVENTOR. 2 I ROBERT J. KUTZLER ATTORNEY y 1954 R. J. KUTZLER STEERING MECHANISM 3 Sheets-Sheet 3 Filed Aug. 8 1951 YAW RATE GYROSCOPE m R 1 WT U VK mJ ATTORNEY Patented July 6, 1954 UNITED STATES PATENT OFFICE STEERING MECHANISM Robert J. Kutzler, St. Louis Park, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application August 8, 1951, Serial No. 240,864

11 Claims. 1

and on the other hand may be operated in an-' other manner so that they are rotated about their supporting axis in opposite directions to act as ailerons. The left and the right wings of the aircraft also have separately mounted therein a rudder. Each rudder consists of two portions hinged together and when operated, these portions project respectively above and below the trailing edge of the wing. In unoperated position, the two portions assume the contour of the wing with their free ends substantially aligned with the trailing edge of the wing.

This invention is an improvement over my, prior application Serial No. 212,345 of February 23, 1951, for Automatic'Pilots primarily adapte for a Flying Wing aircraft.

'In my aforesaid application, briefly, the elevons are operated in opposite directions and one or another of the rudders is operated to place said aircraft in a banked turn. Asa result of the banking of the aircraft, an up elevon signal is provided bythe vertical gyroscope to move both elevons upwardly in the same direction to, preventloss of altitude of the aircraft during said turn. The amount of control surface displacement of either elevon or rudder is limited by a followup drive from the servomotor operating such surface. While the aircraft was making an entry into Such turn, it was discovered that the aircraft had its attitude changed about the pitch axis beyond that desired and in such a direction as to cause it to increase in altitude. This effect apparently was due to the displaced rudder. The rudder while structurally having two portions symmetrically positioned relative to the trailing edge of the aircraft for the purpose solely of increasing the drag of its wing when operated did not derive equal effects from both portions. Actually the. upper portion apparently provides a greater efiect than the lower portion which would account for the tendency of the craft to noseupwardly beyond the amount desired during entry into turns.

The vertical gyro as stated provided an up In one manner of operation,

elevon signal upon tilt of the craft about the I roll axis. This signal tended in itself to increase the attitude of the plane causing it to nose upward. Seemingly, this up elevon signal could be varied or reduced during entry into turns to overcome the effect of the upward change in attitude of the craft due to the displaced rudder. However, rather than modify such control efiect from the vertical gyroscope, I propose to secure the I modifying effect from a separate source which is effective during entry into turns, such entry being considered the portion of the turn in which the'rudder moves to its operated position and returns to its unoperated position which is then succeeded by the steady state portion of the turn.

It is an object therefore of this invention to provide a Flying Wing aircraft having elevon and rudder control surfaces arranged in the wings with a device responsive to operation of a rudder as a consequence of placing said aircraft in a banked turn and for causing operation of said elevons from said device downwardly in' the same direction in proportion to the extent of rudder operation.

. It is a further object of this-invention to opcrate the rudder and elevon control surfaces arranged in the wings of a Flying, Wing aircraft initially to cause a banked turn of the craft and to cause further operation of said elevons in the same direction in response to operation of said rudder previously.

It is a further object of this invention to operate the elevons arranged in the wings of a Flying Wing type of aircraft'so that they operate in the same direction and in accordance with thedifference of the angle of bank of the aircraft and the amount of rudder displacement.

It is a further object of this invention to operate the elevons of a Flying Wing type of aircraft, which have a moment about the roll and pitch axes of the craft, and the rudder, having a moment about the vertical and pitch axes of the aircraft, to set up a desired rate of turn by moving one rudder of said craft and adjusting said elevon control surfaces in opposite directions and thereafter in response to the position of said rudder and to the bank angle of said craft due to operation of said elevons to cause operation of Said elevon control surfaces in the same direction.

It is a further object of this invention to provide a Flying Wing type of aircraft having elevon and rudder control surfaces arranged in the wings with a control signal derived from the bank attitude of the craft during a turn to cause 3 both said elevons to move in an upward. direction and to modify said signal during entry into the turn in accordance with the position of the rudder of said craft.

It is a further object of this invention to provide a Flying Wing aircraft having elevon and rudder control surfaces arranged in the wings with a signal tending to operate both elevons in a downward direction in accordance with the displacement of said rudder which has been positioned to effect an entry or a recovery from a turn.

The above and further objects of the invention will become more apparent hereinafter upon consideration of the following detailed description in conjunction with the accompanying drawings showing a preferred embodiment thereof.

In the drawings:

Figure 1 shows the functional relationship of various control networks for the servomotors that operate the elevons and rudders of the aircraft;

Figures 2a and 2?) together constitute a schematic arrangement of the control system for a Flying Wing aircraft.

Referring to Figure l, for the general aspects of the invention, a right elevon servomotor Ill and. a left elevon servomotor ll operate their respective elevons (not shown) of a Flying Wing type of aircraft. The right elevon servomotor is reversibly controlled from an A. C. discriminator amplifier 14. The left elevon servomotor II is reversibly controlled by a similar A. C. discriminator amplifier IS. The elevons, as stated, may be operated together in the same direction so as to apply a moment about the pitch axis of the aircraft so that they function similar to conventionalelevators. Control voltage signals for the amplifiers for providing this elevator function are derived from a control network 20 and a rudder position network 2i. The control signals from networks 25 2i are connected in series'and applied across a fixed voltage divider l9. The midpoint M of this fixed voltage divider i9 is connected to ground through an aileron control network l 24. It is evident that the phase of the control signal across one-half of the fixed voltage divider is is of opposite phase to that across the other half of the fixed voltage divider. The signals of equal but opposite phase are applied to amplifiers l4 and i5 through the respective rebalance potentiometer networks 88 and 103. These signals on amplifiers i4 and 15 result in the operation of the right and left elevon servom'otors iii and ll so that the elevons are moved in the same direction. A follow-up connection from theelevon servomotors Ill and II to their respective 'rebalance potentiometer networks 83 and it provide a rebal'ancing signal to the respective input signals.

The elevons are also'operable in opposite directions so that they cause the aircraft to bank. Control signals for this operation of the elevons is obtained from the aileron control network I24. A control signal from this aileron network IE4 is applied equally to both amplifiers I4 and i5 and this control signal being of the same phase causes the amplifiers to operate their respective servomotors l8 and II in the opposite directions similar to the operation of the conventional ailerons. A control signal from the aileron control network i2'4 to amplifiers i4, i5 is balanced by the elevon servomotor in each case operating its balance potentiometer netw'orkBB or 163.

Control of the aircraft about its vertical axis is provided by left and right rudders which are respectively operated by left rudder servomotor 2M and a right rudder servomotor 208. One or the other rudder servomotor is alternatively controlled from a rudder servo amplifier 256. Thus rudder servo amplifier is of the A. C. discriminator type and derives its control signal voltages from a rudder control network 258 and a portion of the aileron control network I24. Rebalance of the control network 258 to the rudder servo ampliiier 256 is provided by a sub network 298 therein (shown in detail in Figure 2B) by follow-up connections 3 i d, 3| l extending from the left rudder servomotor 204 and the right rudder servomotor 203.

Rudder position signals are provided in elevator control network 2| by follow-up drives (3H1, 3M) (3! 3l5) extending from the left rudder servomotor 2G4 and the right rudder servomotor 263 to operate network 2|.

For a fuller appreciation of the manner in which control signal voltages are derived, refer=- ence is made to the following detailed description. Referring to Figure 2a, the right elevon servomotor Hi is controlled from its amplifier l4 through automatic steering engage relay l2. The relay when energized serves to electrically connect the amplifier to the servomotor for control of the latter. Similarly the left elevon servomotor H is controlled by its amplifier [5 through an engage relay Iii. Amplifier I4 is provided with power input connections 98, 99 connected to a standard source of alternating voltage and signal input terminals 9B, 97 which are connected to the control signal voltage networks from which is derived a control signal. The direction of rotation of servomotor Hi depends upon the phase relationship of the control signals across terminals 95, 91 with respect to the alternating power voltageacross terminals 98, 99.

Control signals for elevator operation of the elevons is as stated obtained from networks 28, 2!. Network 26 comprises a pitch attitude-craft bank-up elevator signal generator 22; a bank trim generator 55; and a pitch rate generator Bl. Generator 22 comprises a potentiometer 23 having a slider 24 and a resistor 25; a transformer 2? having a primary winding 26 and a secondary winding 2%; an up-elevator potentiometer 29 having a slider 39 and a resistor M, a fixed resistor 3'2; a fixed resistor 33; and a voltage dividing potentio'm'eter 3% comprising a slider as and a re sister 48. Resistor 25 is connected acros the secondary winding 22. Resistor 31 has one end connected through resistors 32 and 33 in series to one end of secondary winding 28. The opposite end of resistor 3i is connected to the remaining end of secondary winding 28. Resistor 49 of the voltage divider potentiometer 33 has one end connected to the junction of resistors 34, 32 and its opposite end connected to slider 3d of up-elevator potentiometer 2Q. Slider 24 is positioned from the electrical center of resistor 25 in either direction in accordance with the direction of craft pitch and in an amount depending upon the magnitude of pitch of the aircraft. This positioning is effected by 'a suitable operating connection 34 extending from a vertical gyroscope 36 to slider 24.

The vertical gyroscope is of the type well known in the art having its rotor mounted within a casing with its spin axis vertical, and the casing supporitng the rotor in turn is mounted in cross gimbals having axes horizontal but perpendicular to one another. The arrangement is such that s u'po'n movement of the craft about its pitch axis, slider 24 is positioned relative to resistor 25.

The slider of the up-elevator potentiometer 29 is positioned from the vertical gyroscope 36 through a suitable operating connection 31 in accordance with the bank attitude of the air-- craft. The operating arrangement between slider 30 and the vertical gyroscope 36 is such that upon tilt of the craft about the longitudinal axis the movement of slider 30 is in the same direction irrespective of the direction of tilt of the aircraft. A conductor 4| extends from slider 24 to a junction 42. Slider 39 of potentiometer 38 may be manually adjusted along resistor 40 and once adjusted is generally so maintained.

Progressing to network 2|, this network comprises a right rudder position potentiometer 42 comprising a slider 43 and a resistor 44; a left rudder position'potentiometer 45 comprising a slider 46 and a resistor 4?; a variable resistor 49;

a secondary winding 50 of transformer 21'; and two equal fixed resistors 5|, 52. Resistor 41 has one end directly connected to an end of secondary winding 50 and its opposite end connected in series with variable resistor 49 to the opposite end of secondary winding 50. Resistor 44 has one end directly connected to an end of secondary winding '50 and its opposite end connected through the variable resistor 49 to the opposite end of secondary winding 50. Resistors 5| and 52 are connected in series and the remaining end of resistor 5| is connected to slider 46 whereas the remaining end of resistor 52 is connected to slider 43. Sliders 43 and 46 are positioned along their respective resistors from one extremity thereof, illustrated, in accordance with the operation of their respective rudder servomotors in a manner to be described. A conductor 53 extends from the junction of resistors 5| and 52 to slider '39 of the voltage dividing potentiometer 38.

Reverting to network 20, trim signal generator 5 5 comprises a potentiometer having a resistor 56 anda slider 51 with the generator additionally including a secondary winding 58 of transformer 21., The secondary windings of the various net- Works as may have been inferred. maybe part of the same transformer 2Ihaving a single primary winding 26; Resistor 56 is connected across the secondary winding '50., Slider 51 is positioned along resistor by a manually operable knob 60.

6 tion depending upon the direction of craft tilt and a distance depending upon the rate of tilt.

It will be evident that terminal 42 and slider 66 are the output terminals of the series connected networks 20, 2|. Across these two output terminals is connected a voltage divider l0 comprisinga potentiometer having a resistor II and a slider I2 with the voltage divider additionally comprising a fixed resistor I3. Resistors II and I3 are connected in series and a conductor I6 extends from the remaining end of resistor II to slider 66, and a conductor I1 extends from the remaining end of resistor 73 to terminal 42. Slider I2 is adjusted along resistor ll in accordance with the proportion of the voltage set up in networks 20, 2| which it is desired to select.

A conductor 84 extends from slider I2 to terminal 85. A fixed voltage divider I9 is connected across the terminals 42, 05. The voltage divider comprises two fixed resistors 80, 'BI of equal electrical resistance. Resistors 80, 8| are connected in series and the remaining end of resistor 80 is connected by conductor 82 to terminal 42 whereas the remaining end of resistor 8| is connected by conductor 83 to terminal 35. Thus the voltage selected by voltage divider I0 is applied across the fixed voltage divider l9, and it is evident that the voltage or potential difference between junction or terminal 8! of resistors 80, BI and terminal 42 is opposite that between terminals 87 and 85.'

The voltage between terminal 81 and terminal 42 is in series with an elevon servo rebalance network 8-8. Network 88 comprises a follow-up potentiometer having a slider 85 and a resistor 90; a voltage dividing potentiometer 92 having a resis tor 93 and a slider 04; a fixed resistor I02; and a secondary winding 9| of transformer 21. Resistor 90 is connected across the secondary winding'iil. Resistors 93 and I02 are connected in series. 1 nectedto slider 80 whereas the remaining end of resistor S02 is connected to terminal 42. A conductor I 0 I- extends from a center tap of secondary winding 9| to terminal 42. Slider 09 is positioned along resistor 90 in accordance with them'ove-f ment of the right elevon servomotor I 5 by a suitable follow-up connection 95. Acondu'ctor E00 extends from slider 54 to signal input terminal A conductor 54 extends from slider 5'? to the June-- tion of resistors 41., 44 with secondary winding 50.

Network 20 lastly includes ajpitch rate signal generator comprising a potentiometer 6| having a slider 62 and a resistor 63; a secondary winding 54 of transformer 21; and a voltage dividing potentiometer 65 having a slider 66 and a resistor 67. Resistor 63 is connected across the secondary winding 64. One end of resistor 61 is connected to a center'tap of secondary winding 64 and the opposite end of the resistor is connected to slider 02. A, conductor 68 extends from the center tap of secondary winding 54 to a center tap of secondary Winding 58 of the trim signal generator 55. Slider B2 is positioned along resistor 83 in either direction from the center thereof by a pitch rate gyroscope 14. .This operation is effected through a suitable operating connection 15. The gyroscope I4 is of a conventional type with the rotor freely rotatable about its spin axis but whose rotation about its precession axis which is at right angles to its spin axis is restrained by suitable means, such as springs. The arrangement is such that upon the craft tilting about its pitch axis the slider 62 is moved relative to resistor 63 in a direc- 56 of amplifier I4. input terminal 3'? of amplifier It is connected to ground.

The; signal between terminal 8? and terminal is applied 'in series with a left elevon rebalance signal generator I03 to amplifier I5. Signal generator I03 comprises a folow-up potentiometer having a slider I04 and a resistor I 05; a secondary winding I00 of transformer:

21; a voltage dividing potentiometer I08 having a slider I00 and resistor H0; and a fixed resistor III. Resistor I 05 is connected across the secondary winding I05. Resistors II0 III are connected in series and the remaining end of resistor H0 is connected by conductor 3 to slider I04 whereas the remaining end of resistor I I I is connected by conductor I I4 to a center tap II 5 of secondary winding I06. A conductor IIl,

extends from the center tap M5 to terminal 85. Slider I04 is positioned along resistor I05 in accordance with operation of the left elevon servomotor II by means of a suitable operating connection H6 whereas slider I09 is manually adjusted along resistor I I 0. A conductor I I9 extends from slider I09 to a signal input connection|20 of. amplifier I5. The other signal in-. put connection I 2| is connected to ground.

The remaining end of resistor 53 is con-' The'remaining control signal Amplifier I5 additionally includes power input connections I22, I23 connected to a suitable source of alternating voltage. Sliders 94 and I09 are adjusted along their resistors 93, I I "concomitantly by a suitable operating connection Continuing to the remainder of the structure,

aileron control network I24 comprises a bank Craft heading-craft bank attitude generator I comprises a heading potentiometer I3I hav ing a slider I32 and a resistor I33; two fixed resistors I34, I; a secondary winding I36 of transformer 21; a bank attitude potentiometer I39 having a slider I46 and resistor I4I; a variable resistor I3B; and a voltage dividing potentiometer I44 having a slider I and a resistor I46. One end of resistor I33 is connected in series with resistor I34 to one end of secondary winding I36 and the opposite end of resistor I33 is connected in series with resistor I35 to the other end of secondary winding I36. Variable resistor I38 and resistor I46 of voltage divider I44 are connected in series and the remaining end of resistor I38 is connected to slider I32 and the remaining end of resistor I46 is connected to a center tap of secondary winding I36. A conductor I41 extends from slider I45 of voltage divider I44 to slider I26 of the bank trim generator I25. Resistor MI is connected across the secondary winding I36. Slider I32 is positioned along resistor I33 from a directional gyroscope I42 by a suitable operating connection I43.

The directional gyroscope I42 is a heading responsive device and is of the type well known in the art having a rotor with a horizontal spin axis carried in a casing. The casing in turn is trunnioned about a horizontal axis at right angles to the rotor spin axis in an outer gimbal. ring.

secondary winding 2 b I56 to'one end of secondary winding I51 and the opposite end of resistor I54 is connected through fixed resistor I to the other end of I51. Resistor I is connected across slider I53 and a center tap of secondary winding I51. A conductor I63 extends from the center tap of secondary winding I51 to terminal I5I. Slider I53 is positioned along resistor I54 by a heading reset signal generator I6I through a suitable operating connection I62. The details of the heading reset generator I6I since they form no part of the present invention and are unnecessary to an understanding of the present invention are omitted. They may be obtained, if desirable, from my aforesaid prior application. The reset generator insures that the craft will regain the stabilized heading.

Manual turn control signal generator I64 comprises a fader potentiometer I65, a pilots potentiometer I69, and a co-pilots potentiometer I13. Potentiometer I69 includes a slider I10 and resistor III with the latter connected across a secondary winding I12 of transformer 21. P0- tentiometer I13 includes a slider I14 and a resistor I15 with the resistor I15 connected across a secondary winding I16 of transformer 21. The fader potentiometer I includes a slider I61 and resistor I66 with the resistor being connected acrosssliders I10, I14. Extending from a center tap of resistor I66 are series connected conductors I68, I18 with the latter being connected to a ground terminal I19. A conductor I11 extends from a center tap of resistor I1I to a center tap of secondary winding I12. Conductor I92 extends from the center tap of secondary winding I12 to ground conductor I18. A conductor I99 extends from a center tap of resistor I15 of the co-pilots potentiometer I13 through a series connected conductor I 9| to ground terminal I19. It is thus evident that the left portion of resistor I66 of fader potentiometer I65 serves as a voltage divider across the pilots potentiometer I69 whereas the right portion of the resistor I66 beyond its center tap forms a volt- 1 age divider for the co-pilots potentiometer I13.

This gimbal ring in turn is rotatable about a vertical axis so that upon change in heading of the craft the slider I32 moves along resistor I33 in a direction dependent upon the direction of change in heading and in an amount depending upon the extent of change of heading. The

directional gyroscope I42 is provided with suitable conventional means I49, generally illustrated, effective during manual changes of heading through the autopilot to prevent operation of slider I32 by the directional gyroscope I42. As

this means forms no part of this invention the details thereof are omitted. The slider I49 of the bank attitude potentiometer I39 is positioned along resistor MI by vertical gyroscope 36 through the suitable operating means 31, E48 in accordance with the direction and magnitude of bank of the aircraft. A conductor I56 extends from slider I46 to a terminal I5I.

'Heading reset generator I52 comprises a potentiometer having a slider I53 and a resistor I54; a'fixed resistor I55; a variable resistor I56; a secondary winding I51 of transformer 21, and a voltage dividing potentiometer I58 having a slider I59 and a resistor I66. One end of resis- A conductor I93 extends backward from slider I61 of the fader potentiometer I65 to the adjustable slider I-59 of voltage divider I523. The signal generators of the network I24 which are thus connected in series develop an output voltage, when adjusted, between the ground terminal I19 and a center tap Iili of secondary winding I28 of the bank trim generator I25. A voltage divider I32 is connected across the terminals I19 and center tap I8I. This voltage divider comprises a potentiometer resistor I63, its coacting slider and additionally includes a fixed resistor I35. Resistors I93 and I85 are connected in series and the remaining end of resistor I83 is connected by conductor I86 to center tap I8I whereas the opposite end of resistor I65 is connected by conductor 81 to ground terminal I19. A conductor I63 extends from slider I84 to terminal 91 in the elevator network 20.

It is now apparent that with no signal voltage generated in network I24 that there will be no voltage across voltage divider I62. Consequently, terminal 81 is at the same potential as ground terminal I19. Thus any signal in network 29 will result, as stated, in a voltage between terminals 42 and terminal 81 which is opposite in phase to the voltage between terminal 65 and terminal 81 with the latter now being at ground potential and thus common to the ground terminals 91 and tor I54 is connected through variable resistor I 2| 0f amplifiers I4 and I5. Thus in all sub- I work I24 or from the latter along with the network terminal I19 serving as a ground for both networks.

The rudder control apparatus is mainly illustrated in Figure 2B. In this figure, a rear portion of one wing is shown in section. This portion includes a rudder having the upper portion I95 and lower portion I96 which in dotted position assume the contour of the wing but when operated (full line position) move outwardly from the top and bottom portions of the wing. Operating links I91 and I98 extend from the wing portions I95 and I96 to a common pivot on rack bar I99. Rack bar I99 is longitudinally operated by a pinion 200 carried by a drive shaft 202.

For positioning the rudder members I95 and I96 there is provided a right rudder servomotor 203. The motor 203 is a reversible D. C. series motor and comprises field windings 205, 206; a pulsing clutch winding 201; armature 208; motor drive shaft 2I2; magnetic clutch 2I0; and output shaft 2 connected to drive shaft 202. Pulsing clutch solenoid 201 has one end connected to a junction of field windings 205, 206 and its opposite end is connected in series with armature 203 to a ground conductor 2| 3. The magnetic clutch 2I0 is interposed the drive shaft 2 l2 and output shaft 2| I so that with the clutch energized the drive shaft 2 I2 and output shaft 2 are operatively connected.

Arrangement of the pulsing clutch and its winding 201 is such that with the motor energized, the motor operates the output shaft 2 without a brake being applied thereto. However, with the motor deenergized a brake is applied to the output shaft 2 so that it is held against movement until the motor is again energized. The motor pulsing clutch-brake arrangement is well known in the art. (See the patent to Lear 2,267,114.)

The left rudder (not shown) is positioned by a servomotor 204 similar to motor 203 and having;

motor windings 2| 4, 2I5; pulsing clutch Winding 2I6; motor armature 2I1; drive shaft 2! 9; magnetic clutch 2I8; and output shaft 220. One end of pulsing clutch winding M6 is connected to a common junction of windings 2I4, 2I5 and the other end of pulsing clutch winding 2I6 is connected in series with the armature 2| 1 to a connected to in contact 232 of relay 224 and:

winding 2I5 is connected to out contact 220 of relay 222. One end of operating coil 225 of relay 222 is connected to ground. A conductor 234 extends from the other end of coil 225 through a normally closed single pole single throw switch 235 to a source of D. C'. voltage such as battery 236. Operating coil 230 of relay 224 has one end connected to ground and its otherend connected .by conductor 23! and a normally closed single pole single throw switch 238 to D. C. source 236.

These relays are of the single;

- The switches 235 and 238 are operated by the left and right rudders respectively. As the rudder of the respective switch moves to closed position, such switch is closed but upon movementof the rudder to open position, its corresponding switch moves to open position. A suitable operating connection 240 is therefore provided between the shaft 220 of servomotor 204 and the switch'arm of switch 235 and a similar operating connection 241 is provided between the drive shaft 202 and the switch arm of switch 238.

Arm 226 of relay 222 is connected through a rudder engage relay 242 to an in contact 243 of an amplifier relay 244. Relay 244 includes an operating coil 245 and an operable arm 246. Arm 246 is connected to a source of D. C. voltage 236. Arm 23I of relay 224 is connected through a second rudder engage relay 241.to an in contact 248 of an amplifier relay 249. Relay 249 includes an operating coil 250 for an arm 25 I. Arm 25I is connected to the source of D. C. voltage 236.

Relays 244 and 249 are part of a discriminator type amplifier having A. C. control signal voltage input connections 252, 253, and A. C. power input connections 254, 255. The amplifier functions to operate one or the other of relays 244, 249 depending upon the phase relationship of the control voltage across connections 252, 253 with respect to the voltage from the power source supplied to connections 254, 255. A suitable form of amplifier is disclosed in Patent 2,425,734 dated August 19, 1947, to Willis H. Gille et al. The form of amplifier and servomotor used for operating the rudders is also suitable for operating the elevons of the aircraft. Control signals across amplifier input connections 252, 253 are provided by a rudder control network 253 and a portion of the aileron control network I24. Network 258 comprises a yaw rate signal generator 260, a trim signal generator 268, a heading stabilizing signal generator 213, a yaw reset signal generator 265, and a rebalancing signal generator 298.

Signal generator 260 consists of a potentiometer having a slider 26! and a resistor 262 which resistor is connected across a secondary winding 263 of transformer 21. along resistor 262 in either direction from its Slider 26I is positioned midpoint by a yaw rate gyroscope 264, the movement being effected through a suitable operating connection 265. The yaw rate gyroscope is of the two degree of angular freedom type with movement of the rotor about one axis being restrained so that the slider 26I is moved relative to resistor 262 in accordance with the rate of change of heading of the craft. A conductor 266 extends from input connection 252 of amplifier 256 to slider 26L to a center tap of secondary winding 263.

Signal generator 268 consists of a potentiometerhaving a slider 269 and a resistor 210 with the resistor connected across a secondary Winding 2H of transformer 21. A conductor 212 extends from a center tap of secondary winding 21I Slider 269 may be manually positioned along resistor 210.

Si nal generator 213 comprises a potentiometer having a slider 214 and a resistor 215; fixed resistors 216, 211; a secondary winding 219 of transformer 21; and a voltage dividing potentiometer .218 having a resistor 280 and a slider 28L One with resistor 21! to the remaining end of secondary 219. Resistor 233 of the voltage dividing potentiometer 2'13 is connected across slider 2'14 and a center tap of secondary Winding 279. Slider 234 is adjusted along resistor 235 in either direction from the midpoint thereof in accordance with craft heading changes by a suitable operating connection 232 extending from operating means 143 connected to directional gyroscope 142. The extent of movement of slider 2'14 depends upon the magnitude of change in heading while the heading is being stabilized. A conductor 283 extends from slider 253 to the center tap of sec-- ondary 219.

Signal generator 235 comprises a potentiometer having a slider 283 and a resistor 23?; a variable resistor 238; a fixed resistor 239; a secondary winding 233 of transformer 21; and a voltage dividing potentiometer 291 having a slider 292 and a resistor 293. One end of resistor 28? is connected in series with variable resistor 288 to one end of secondary winding 230. The other end of resistor 23'! is connected through fixed resistor 289 to the remaining end of secondary winding 233. Resistor 233 of the voltage dividing potentiometer 295 is connected across a center tap of secondary winding 230 and slider 286. Slider 283 is positioned along resistor 231 by a yaw reset signal generator 294 the movement being effected by a suitable operating connection 235. Since the details of the reset signal generator 294 are unnecessary for an understanding of the present invention and are not to be claimed herein, reference is made to my prior application for more full disclosure thereof. A conductor 296 extends from the center ta of secondary winding 230 to slider 281 of the voltage dividing potentiometer 218.

Signal generator 298 comprises a left rudder rebalancing potentiometer having a slider 299 and resistor 3013; fixed resistors 39!, 332; a right rudder rebalancing potentiometer having a slider 333 and resistor 334; and a voltage dividing potentiometer 336 having a slider 33? and a resistor 338. Resistors 303, 361 are connected in series and the combination is connected across the secondary winding 335; resistors 392, 333 are connected in series and this combination is similarly connected across the secondary winding 305. Resistor 338 of the voltage dividing potentiometer 336 is connected across sliders 299, 303. Slider 239 is positioned along resistor 300 in accordance with the movements of the. left rudder servomotor by a suitable operating connection 313, 220. Slider 333 is positioned along resistor 304 in accordance with the movements of the right rudder servomotor by a suitable operating connection 3 l l, 21 I. A conductor 333 extends from slider 292 gig voltage dividing potentiometer 291 to slider Reference is made to Figure 2a for'the remaining portion of the input control network for rudder amplifier 256, This remaining portion of the control circuit comprises a turn coordination potentiometer 3H], heading reset signal generator i552, and the manual turn control network 1E4. Turn coordination potentiometer 3 Hi comprises a slider 311 and resistor 312. Resistor 312 is connected across a center tap of secondary winding 333 of signal generator 133 and terminal 131. Slider 31 I is manually adjusted along resistor 3 l 2. A conductor 3! extends from slider 311 to slider 33'! of the voltage divider 333 in signal generator The nal generators 152 and W4 have been,

i2 previously described in connection with the aileron control network 124.

The left rudder servomotor 234 in addition to operating the arm of single pole single throw switch 235 and the slider 293 of the'network 238 additionally through a further operating connection 31 4 adjusts slider 43 in the signal generator 21. Similarly the right rudder servomotor 233 in addition to positioning the arm of single throw switch 238 and the follow-up slider 333 of signal generator 238 through a further operating connection 315 operates slider 43 in network ii. The movements of sliders 4e and 33 along their respective resistors 45, 44 are in accordance with the movements of the rudder servomotors associated therewith and thus the movement of slider 43 or 43 is in accordance with the operation of its rudder. In view of the fact that a rudder merely moves from closed to open position the follow-up sliders 299, 333 as well as sliders 43 and 43 are positioned at one extremity of their respective resistors with the rudders closed. Operation of its associated rudder from closed toward open position causes the movements of these sliders away from the end position on their resistors.

Operation In operation, the aircraft control surfaces are generally directly manually controlled until the craft has attained a desired heading and attitude. If automatic control be thereafter desirable, a single pole single throw switch 3!! maybe operated. Closing of switch 31 effects energization of the magnetic clutches 2M, 213' of the rudder servomotors 203, 234 from battery 233 through conductors 323-, 321, 322; switch 311, to conductor 323 and thence in parallel, clutch 213, conductor 221 or conductor 324, clutch 210, conductor 2'13, to ground and return to battery ground 325 whereby the rudders of the aircraft are connected to their respective servomotors and held in braked or locked position while the servomotors are deenergized'. Similar magnetic clutches may also be provided for the elevon servomotors 10, 1'1 and simultaneously energized. Closing of the switch 31'! also energizes the rudder engage relays 242, 2 1! from closed switch arm 311, conductor 323 thence in parallel both relays. The elevon engage relays 52, l 3 likewise may be concurrently energized fro-m switch 311. Thus, the control surfaces are engage-d with their respective servomotors, and the servomotor windings in turn may be energized from D. C. source 233 through the amplifier relays.

With'the automatic steering mechanism engaged with the control surfaces of the aircraft the craft is stabilized about the pitch, roll, and vertical axes. Should the craft tilt about the pitch axis from its stabilized attitude, the vertical gyroscope 36 operates slider 24 so that the ele vator network 29 becomes electrically unbalanced. A voltage signal is therefore applied to the respective amplifiers i4, 15 resulting in the operation of the elevon servomotors 13 and 11. The servomotors in'addition to positioning their elevons in the same direction operate their follow-up sliders 89, 104 to proportion the movements of their respective elevons in accordance with the amount of change in pitch attitude. As the craft returns towards its normal attitude, slider 23 is moved toward its normal position on resistor 23. This reverse movement of slider 24 decreases the unbalance of network 23 and decreases therefore the signal voltage between terminal 8'! and ter- 7 axis.

up-elevator potentiometer and slider I43 of the craft bank attitude potentiometer I39. The movement of slider I40 generates a signal between slider I40 and the center tap of secondary winding I36 which is applied across the voltage divider I82 of network I24. A portion of this voltage is selected by slider I84 and applied I equally to elevon amplifiers I4 and I5. This control signal being of the same phase on-each amplifier through a cross connection causes the servomotors I and II to position their elevon control surfaces in o posite directions. This movement of the control surfaces tends to restore the craft to its original attitude about the roll As before, .movement of the craft back toward normal moves the slider I40 back toward its normal position until the elevons are again in normal position with the normal attitude about the roll axis resumed.

In view of the fact that the elevon which is positioned downwardly tends to create a drag on the craft which would tend to cause it to change its heading with respect to the vertical axis, a signal from the bank attitude potentiometer I33 is also applied through the voltage divider 3H] and conductor 3| 3 to the rudder network .258. Thus, with the'right elevon lowered, the left rudder would be operated toward open position to oifset the tendency of the craft to change heading toward (the right about the vertical axis.

Since a craft in a banked attitude tends to lose altitude, the slider 30 is positioned along resistor 3I in accordance with changes in attitude of the craft about the roll axis. This movement of slider 30 unbalances the elevator network 20 causing both elevons to be moved upwardly in proportion to the up-elevator signal. The subsequent position of both elevons in the same direction prevents loss of altitude of the craft while banked.

If the craft changes heading, while under stabilized flight, the directional gyroscope I42 operates slider 132 of the aileron network I24 and also operates slider 274 in the rudder network 258 whereby the elevons and a rudder are operated to place the craft in a banked turn. As the craft banks, the vertical gyroscope 35 applies an up-elevator signal by positioning slider 30 in signal generator 22 and also generates a signal in network I24 by the adjustment of slider I40 to return the elevons toward normal position. A portion of the signal obtained from movement of slider I40 is introduced into the rudder network 258 by voltage divider 3I0 tending to move the operated rudder toward its closed position.

When the craft has attained its maximum bank, it is in the steady state portion of the turn. The portion of the turn up to the point when the steady state is attained is known as the entry into the turn. During the entry of the craft into the turn, the craft unless prevented would tend to gain altitude. This gain in altitude during entry into the turn is due to the different effects produced by the upper and lower portions of the operated rudder such as portions I95, I96 of the rudder shown in Figure 21) or corresponding parts of the other rudder not'shown. -While it was intended that the upper and lower portions of rudder being displaced angularly in equal amounts would have equal but opposing effects about the pitch axis and thus merely increase the drag of the wing, it appears that actually the upper portion of the rudder has a greater effect than the lower portion with respect to the moment about the pitch axis of the craft and causes the craft to gain in altitude.

In order to prevent this gain in altitude during entry into the turn due to a displaced rudder, the operated rudder servomotor will position slider 43 or slider 46 innetwork 2|. Displacement of either slider 43 or 46 will result in a voltage signal across conductors 53 and 54 which is of the same phase irrespective of which slider is moved. This voltage between conductors 53, 54 is provided in elevator network 20 and serves to effect movement of the elevons downward. This downward operation of the elevons due to the position assumed by the operated rudder offsets the tendency of the craft to gain altitude during entry into the turn. As soon as the craft is in the steady state portion of the turn, the rudder is closed and the down elevon voltage is removed. Thus, the down elevon signal from network 2I prevents gain in altitude during entry into the turn and'the up elevon signal due to movement of slider 30 of the up-elevator network 22 serves to maintain altitude of the aircraft during the steady state portion of the turn.

The operation for heading changes by means of the manual turn control networks I 69 and I13 is similar to that described for heading changes from the directional gyroscope I42 in that aileron action of the elevons and operation of a rudder causes entry into a turn. During this entry, the vertical gyroscope functions to return the elevons and rudder toward unoperated position and also functions to apply up-elevon. The operated servo functions to provide a down elevon effect. The directional gyroscope is conventionally rendered ineffective to oppose the manual change in heading. In the steady state part of the turn, the servo position effect is removed but the vertical gyroscope up-elevon effect continues. On recovery from the turn in order to follow a selected heading, the servo position on the elevons is again introduced.

It will now'be apparent that there has been provided an improvement in an automatic steering apparatus for a Flying Wing aircraft which maintains the altitude of such craft during banked turns and this is achieved by providing, as it goes into the banked turn, a down elevon effect in proportion to rudder operation during this entry into the turn but which effect is withdrawn during the steady state portion of the turn when the rudder is returned to unoperated position. Thereafter, in the steady state portion of the banked turn, the elevons provide an up-elevator effect in proportion to the bank attitude to compensate for the decreased vertical lift of the craft which would otherwise, cause it to loose altitude. It is also evident. that this efiect of down elevons is also applied during recovery from the turn when the opposite rudder is positioned as the craft assumes a new heading.

While but one embodiment of the invention has been disclosed, it will now be appreciated that it may assume other constructions; therefore, it is desired that the invention be not restricted to the specific form used for illustrative purposes but as defined by the accompanying claims.

I claim as my invention:

1. Control apparatus for an aircraft having a first control surface arranged ina wing of said craft that produces a moment about the craft vertical and pitch axes when displaced from a normal position and a second and third, control surface arranged in the wings of said craft and producing jointly a moment about the craft roll axis when said second and third. surfaces are positioned in opposite directions from a normal position and jointly producing a moment about the craft pitch axis when said surfaces are positionedin the same direction from a normal position; said apparatus comprising a first control mean adapted for operating said first surface; a second control means adapted for operating said second and third surfaces; heading change detecting signal means connected. to both control means for operating both control means to effect operation of said three surfaces to place said craft in a banked turn; and signal means displaced with said first surface and connected to said second control means for further operating said second control means tocffect movement of said second. and third surfaces to pro duce. a moment about the pitch axis opposing the; moment about this axis of said first. surface.

2; The apparatus of claim 1 with follow-up means driven with each control surface and effective on its corresponding control means to provide a proportional movement to each said surface.

3. The apparatus of claim 2 with means responsive' to the banked attitude of said aircraft and operating on said first and second control means to cause return movement of said first, second, and third control surfaces to limit the bank of said aircraft to the extent of operation of said heading change means.

4. Control apparatus for an aircraft having a first control surface arranged in a wing that produces a momentabout the craftvertical and pitch axes and a second and third control surface, arranged in the wings of said craft and jointly producing a moment about the craft roll axis when said second and third. surfaces are positioned in opposite directions and jointly producing a moment about the craft pitch axis when said surfaces are positioned in the same direction; said apparatus comprising a first balanceable control means for operating said first surface; a second balanceable control means for operating said. second and third surfaces; means responsive to change in heading of said craft adapted for operating both balanceable control means toplace said craft in. a banked turn; follow-up means operated by said surfaoesand operating on said cor esponding control means tolimit operation of said first, second, and third surfaces in proportion to. said change in heading; means responsive to banked attitude of said craft adapted for operating said first and second control means to effect return movement of said operated control surfaces toward unoperated position; and further means operated in accordance with displacement of said first surface and operating said second balanceable control means to effect operation of said second and third surfaces to produce a moment opposing a moment of said first surface about the pitch axis.

5. Control apparatus for an aircraft having two pairs of control surfaces arranged in the trailing edge of the wings of said craft, said apparatus comprising: motor means for projectin one control surface of one of said pairs so as to receive on said surface an impact of the air stream and thus derive a moment tending to rotate said craft about its vertical axis: and also about its pitch axis; signal: means responsive to the displacement of said' one surface; control means operated by said signal means; and motor means operated by said control means for moving the other pair of control surfaces in the same direction to receive the. impact of the air stream thereon and thus apply a moment to said craft about said pitch axis which opposes the moment of said one surface about said pitch axis.

6-. Control apparatus for an aircraft having elevon control surfaces operable in the same or opposite directions and rudder control surfaces, said apparatus comprising: stabilizing means connected to said elevon and rudder surfaces for stabilizing said aircraft about the vertical, bank, and pitch axes; manually operable turn control means cooperating with such stabilizing means for initiating a turn by operating a rudder and adjusting the bank angle of said aircraft by positioning said elevonsin opposite directions; such turn control means coacting with such stabilizing means for adjusting the pitch attitude of said aircraft; and further means responsive to positioning of said rudder surface and operable through said pitch control means to effect operation of said elevons in the same direction to oppose the change in pitch attitude of said craft occasioned by the displacement of the rudder surface.

'7. Control apparatusfor an aircraft having a first control surface arranged in a wing of said craft that produces av moment about the craft vertical and pitch axes and a second and third control surface arranged in the wings of said craft and producing a moment about. the craft roll axis when said second and third surfaces are positioned in opposite directions and producing a moment about the craft pitch axis when p0sitioned in the same direction, said apparatus comprising a. first control means for operatin said first surface; a second control means for operating said second and third surfaces; heading responsive means for operating both control means to effect operation of said first surface and to effect operation of said second and third surfaces in opposite direction to place said craft in a banked turn; position maintaining means responsive to the bank of said craft. and, operating said first and second control means to effect movement of said, first surface and said, second and third surfaces, to their unoperated position; and means effective during operation of, said first surface for operating said second control means to cause rotation of'said second and third surfaces in the same direction to produce a moment opposing the moment of said first. surface about the pitch, axis.

8. In control apparatus for an aircraft. having a rudder control surface exerting a moment. about the vertical and pitch axes of the aircraft and elevon control surfaces operable in the. same direction to exert a moment about the pitch axis of said craft and, operable in opposite directions to effect a moment, about the roll axis of they aircraft, in combination: adjustablemeans adapted for operating the rudder for causing. a turn of the aircraft at some selected rate; adjustable means adapted for operating the elevons in opposite directions for causing a bank of the craft; manual control means; having connections for'simultaneously operating both. adjustable means; and means operated proportion to the displacement of said rudder and having connections to the elevon operating means for operating both elevon control surfaces in the same direction to apply a moment about the pitch axis opposin a moment of the operated rudder about said pitch axis.

9. Control apparatus for an aircraft having control surfaces for causin turning of the craft about the vertical axis and control surfaces operable in opposite or the same direction for alternatively causing rotation of the craft about the bank and pitch axes, in combination: first means for operating said first named surfaces for causing a turn of the craft at a selected rate; second means for operating the second named surfaces in opposite directions for causin a bank of the aircraft; means for resetting simultaneously both operating means; and further means responsive to the operated position of said first named surfaces for operating said last named surfaces in thesame direction to oppose the turning effect about the pitch axis of the operated first surfaces.

10. Control apparatus for an aircraft having a first control surface exerting; when displaced from a normal position a moment about the vertical and pitch axes of the aircraft and second control surfaces for exerting when displaced from a normal position a moment about the pitch axis when operated in the same direction, in combination: servo means for operating the first control surface; servo means for operating the second control surfaces; a heading responsive device adapted on change in craft headin for controlling the operating means for said first control surface; and means responsive to operation of said first control surface for controlling the operating means for the second control surfaces to displace the second control surfaces whereby they exert an opposing moment to the first control surface about the pitch axis.

11. Control apparatus for an aircraft having two sets of control surfaces, one set causing the craft to move about one of its axes, the other causing the craft to move about an axis perpendicular to said one axis; a motor means for pcsitioning the one set of control surfaces; a motor means for positioning the other set of control surfaces; means for controlling the first motor means to cause said craft to change heading; and means responsive to the extent of operation of the first motor means for controlling the extent of operation of the second motor means.

No references cited. 

